Engine power unit

ABSTRACT

Disclosed is a power unit and engine wherein reciprocal motion of piston means are transformed into rotary motion of an output shaft without the aid of cranks and connecting rods. More particularly is disclosed a power unit which includes at least one cylinder piston assembly and an axially aligned rotor cam means connected to a drive shaft which means, in operative association with the piston which is guided for reciprocation only, transforms the reciprocal motion of the piston into rotary motion of the drive shaft. In the preferred form there is employed two substantially identical but opposed cylinder, piston and rotor assemblies in axial alignment, with means associated with the opposed pistons for causing them to reciprocate in unison. The opposed rotor means are connected to a unit shaft and are hollow, cylindrical rotors having annular cam surface means which in operative association with piston cam rollers transforms the reciprocal motion of the pistons into rotary motion of the unit shaft. The means for causing said pistons to reciprocate in unison comprises rod means between the pistons and slidably received within a bore through the unit shaft. The length of the rod means is such to control the separations of said pistons whereby a power stroke of one piston effects the return stroke of the opposed piston and maintains the cam rollers of the opposed piston in disengagement from the cam surface means of its associated rotor means during its return stroke. In addition is disclosed a steam engine with the operative association of a plurality of these power units about a common, central output drive shaft. Timed valve means control the flow of steam through the cylinders of the units and a mechanism is provided for advancing the valve means in response to an increase in rotation of the central drive shaft. Further a lubrication system is disclosed for such engine. When a power unit is adapted in an internal combustion engine, there is provided a power storage piston which stores energy from the initial impingement caused by firing the working fluid and which subsequently releases substantially all the stored energy during the power stroke of the piston whereby the sudden build-up of stress in the cam engaging surfaces is reduced.

United States Patent 1 Striegl 1 July 17, 1973 ENGINE POWER UNIT [75] Inventor: George Striegl, Prescott, Ontario,

Canada [73] Assignee: Temco Contact Ltd., Ottawa,

Ontario, Canada 22 Filed: June 18, 1971 21 Appl.No.: 154,446

[30] Foreign Application Priority Data Mar. 31, 1971 Canada 109261 [52] US. Cl. 92/146, 74/55, 74/56, 92/91, 123/56 C, 123/58 R [51] Int. Cl. F0lb l/00, Fl6h 25/16, F02b 75/26 [58] Field of Search 123/58 R, 58 AB, 123/58 AM, 56 C, 56 R; 74/56, 55; 92/91, 31, 146, 467

[56] References Cited UNITED STATES PATENTS 1,052,763 2/1913 Stone et a1 92/31 1,076,807 10/1913 Anderson 123/58 AB 1,339,276 5/1920 Murphy 123/58 AB 1,497,635 6/1924 Parrish.... 74/56 R 1,572,068 2/1926 Gould 92/31 R 1,813,259 7/1931 Schick 74/56 X 2,320,526 6/1943 Landis 123/58 AZ 2,401,466 6/1946 Davis et a1. 74/56 X 3,396,709 8/1968 Robicheaux 123/58 AM X 3,598,094 8/1971 Odawara 123/58 R Primary Examiner-Wendell E. Burns Att0rney-Watson, Cole, Grindle & Watson ABSTRACT Disclosed is a power unit and engine wherein reciprocal motion of piston means are transformed into rotary motion of an output shaft without the aid of cranks and connecting rods. More particularly is disclosed a power unit which includes at least one cylinder piston assembly and an axially aligned rotor cam means connected to a drive shaft which means, in operative association with the piston which is guided for reciprocation only, transforms the reciprocal motion of the piston into rotary motion of the drive shaft. In the preferred form there is employed two substantially identical but opposed cylinder, piston and rotor assemblies in axial alignment, with means associated with the opposed pistons for causing them to reciprocate in unison. The opposed rotor means are connected to a unit shaft and are hollow, cylindrical rotors having annular cam surface means which in operative association with piston cam rollers transforms the reciprocal motion of thepistons into rotary motion of the unit shaft. The means for causing said pistons to reciprocate in unison comprises rod means between the pistons and slidably received within a bore through the unit shaft. The length of the rod means is such to control the separations of said pistons whereby a power stroke of one piston effects the return stroke of the opposed piston and maintains the cam rollers of the opposed piston in disengagement from the cam surface means of its associated rotor means during its return stroke. In addition is disclosed a steam engine with the operative association of a plurality of these power units about a common, central output drive shaft. Timed valve means control the flow of steam through the cylinders of the units and a mechanism is provided for advancing the valve means in response to an increase in rotation of the central drive shaft. Further a lubrication system is disclosed for such engine. When a power unit is adapted in an internal combustion engine, there is provided a power storage piston which stores energy from the initial impingement caused by firing the working fluid and which subsequently releases substantially all the stored energy during the power stroke of the piston whereby the sudden build-up of stress in the cam engaging surfaces is reduced.

29 Claims, 32 Drawing Figures PATENIEB JUL 1 7 I973 SHEET 01 [1F PAIENIED JUL 1 new SHEEI 02 HF m mm PATENIED JUL I 7 I975 SHEET U3UF 17 l I"85i PAIENIED JUL 1 mm SHEET 0 5 HF PATENIED M v 1 W BIZ SHEET [)8 BF PATENTEDJUL 1 mm SHEET 1 0 U? m Sow OON BNNN

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PAIENIEUJUUTI973 3.745.887

SHEET 11 HF 17 82 I56 FIG. I4 15s 1 PATENIEB JUL 1 1 ma SHEET 12 0F PATENTEU JUL I 75 SHEET 1 3 0F PAIENFED 1 7 3. 745 L. 8 87 SHEET 114 OF 11 FIG. 23 F/6.24 F7625 EEK 27 FIG.26 H628 279 CYLINDER HEAD I24 CYLINDER HEAD I240 (LEFT END) (RIGHT END) FIG. 30

PISTON POSITION CYLINDER ACTIVITY VALVE TIMING UNIT m PRESSURE "As oz r o axunusr #:AUST a A 3 4 2 3 4 I 2 g B 4 I 2 3 4 I 2 3 3 C I 2 3 4 I 2 3 4 E D 2 3 4 I 2 3 4 I Q E I 2 3 4 l 2 3 4 ff F 2 3 4 I 2 3, 4 I Z G 3 4 I 2 3 4 I 2 E H 4 I 2 3 4 I 2 3 360'-IREV. Shufl I52- PATENTEU JUL 1 mm SHEET 18 0F omw NOu

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ENGINE POWER UNIT FIELD OF THE INVENTION This invention relates to power units and more particularly to improvements in positive displacement power units wherein reciprocal motion of a piston is mechanically converted into rotary motion, and vice versa, without the use of cranks, connecting rods, and the like. Further, this invention relates to the operative association of at least two such units in an engine with suitable rotary valve, and valve advance means for controlling the flow of a working fluid to the units and with suitable lubrication means for the engine.

BACKGROUND Modern day positive displacement power units conventionally employ a crankshaft and connecting rod to convert the reciprocating motion of the piston to rotary motion of a shaft, and vice versa. The internal combustion engine, commonly found in todays automobiles, and the steam engine found in several of todays power plants are examples of engines employing this type of conventional power unit construction.

It is well known that crankshafts and connecting rods contribute to problems in the dynamic balancing of modern day engines. In addition, the use of a crank creates side thrust producing ovalization of the cylinder and serious wear on the piston and results in a loss of power transmitted causing decreased efficiency. Moreover, power units employing cranks and connecting rods to convert reciprocal motion into rotary motion and vice versa are relatively large and heavy as a result of the space required to accommodate the translational movement of the connecting rod following the circle of the crank.

In my invention as disclosed in US. Pat. No. 3,219,669 granted Apr. 21 1964 I disclose a basic power unit wherein rotary motion is mechanically converted into positive displacement without the use of a crankshaft mechanism. My power unit as diclosed in that patent overcomes the disadvantages of prior art units by transmitting power through a wedging or camming action between substantially in line stators and rotating, reciprocating pistons. No crankshaft mechanism is employed and the unit is substantially selfbalanced with little uneven wear resulting in the walls of the cylinders.

It will be appreciated however that in the power unit as disclosed in that patent, excessive heat is developed as a result of friction between the rotating wedge or cam surfaces of the piston and the stationary wedge or cam surfaces of the stator. In addition, heat is developed within the cylinders as a result of rotation of the pistons therein and such heat is not readily dissipated from the unit. Heat would particularly be a problem if a plurality of units as disclosed in that patent were coupled within a larger housing to form a composite power unit or engine.

OBJECTS My present invention uniquely overcomes the disadvantages of the prior art power units utilizing crankshaft mechanisms and of my prior device in providing a reliable, durable power unit which is relatively inexpensive, is substantially self-balanced and has significantly less frictionally engaging surfaces and accord ingly heat dissipation problems.

It is an object of this invention to provide an improved power unit wherein power is transmitted from a reciprocating member to a rotary output member, without the use of cranks and and connecting rods.

It is a further object of this invention to provide an improved power unit wherein the linear displacement of a non-rotating piston means on its power stroke is transformed into rotary output motion through a wedging or camming action between the piston means and a hollow, cylindrical, axially aligned rotor means, with little friction between engaging surfaces.

It is a still further object of this invention to provide a power unit wherein two such piston means and rotor means are in axially opposed relationship and associated in such manner that the linear displacement of each piston means on its respective power stroke is transformed into a rotary output while such piston dis placement effects the return stroke of the other piston means, the pistons thereby reciprocating substantially in unison.

It is still a further object of this invention to provide a power unit including opposed and axially aligned piston and cylinder means and interposed power transmitting rotor means wherein reciprocal non-rotary motion of each opposed piston means in its respective cylinder is transformed into rotary motion of said power transmitting rotor means, the rotor means consisting of opposed angularly ofl'set cam surface means each of which, in cooperation with operatively associated cam means of the piston means causes rotation of said rotor means, and the opposed piston means operatively associated for reciprocation in unison whereby the power stroke of each piston means effects the return stroke of the other piston means without engagement between the cam means of the returning piston means and its associated cam surface means, thereby periodically relieving the stress due to contact between the piston means and cam surface means and permitting a cam surface profile with a longer power stroke surface which enhances net power output of the unit.

It is a further object of this invention to provide in a power unit, a power storage piston wherein a part of the energy resulting from the impingement of an active working fluid on the piston is stored therein during the initial part of its power stroke and subsequently substantially released during the latter part of its power stroke.

It is a still further object of this invention to provide an engine embodying a plurality of such power units about a central drive shaft, operatively associated through suitable gearing and valve control means.

It is yet a further object of this invention to provide a dynamically balanced steam engine embodying a plurality of my power units operatively associated about a common central drive shaft for transmission of power between a working fluid input and rotary output of the common drive shaft with valve control means for controlling in suitable timed relation the flow of working fluid to the plurality of power units and lubrication means suitably lubricating the reciprocating and rotating elements.

It is yet a further object of this invention to provide in such a steam engine having rotary valves, a valve advance mechanism which is simple in construction yet reliable in performance and consists of means operatively connected to said drive shaft to counterrotate in response to the speed of said shaft the valve sleeve means housing the rotary valves.

It is a still further object of this invention to provide in such a steam engine a reliable lubrication system which effects continuous lubrication of all reciprocating and rotary elements of the engine.

Other objects and advantages of this invention will become more apparent upon a full appreciation of the drawings attached hereto, illustrating, in conjunction with the following description, the preferred forms of my invention.

FIG. 1 is an elevational view partially in section of an internal combustion engine in which my power unit is embodied;

FIG. 2 is a sectional plan view of the engine of FIG. I and shows in section the piston and rotor means and shows further a power take off shaft;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is an enlarged view of part of FIG. 2 taken within line 5-5 thereof;

FIG. 6 is an enlarged view of part of FIG. 3 taken within line 6-6 thereof;

FIG. 7 is an exploded perspective view of the power transmitting elements in the engine of FIG. 1;

FIG. 8 is a plane developed view illustrating schematically the rotor means and piston drive rollers of the power transmitting elements in the engine of FIG. 1, with FIGS. 5 & 6;

FIG. 9 is an elevational view of a steam engine embodying a plurality of my power units;

FIG. 10 is a left end view of the engine in FIG. 9;

FIG. 11 is a sectional view taken along line 11-11 of FIG. 10 showing generally a single power unit in the steam engine;

FIG. 12 is a sectional view taken along line 12-12 of FIG. 10 showing two diametrically opposite power units in the engine of FIG. 9, one of the units only being shown in full section;

FIG. 13 is a vertical, sectional view taken along line 13-13 of FIG. 9 showing generally the main gear assembly for the steam engine, with FIG. 10;

FIG. 14 is a sectional view taken along line 14-14 of FIG. 9 showing, in section, the cam rotor elements of the steam engine;

FIG. 15 is a broken sectional view taken substantially along line 15-15 of FIG. 9 showing, in part, the piston and cylinder units and cover plate of the steam engine;

FIG. 16 is a sectional view taken along line 16-16 of FIG. 9 showing in part cylinders and a cylinder head of the steam engine;

FIG. 17 is a vertical sectional view taken along line 17-17 of FIG. 9 showing the valves and valve control mechanism in the left end cylinder head of the steam engine;

FIG. 18 is a plan view in section, taken along line 18-18 of FIG. 9 showing the valves and valve control mechanism;

FIG. 19 is a partial sectional view of a cylinder head valve sleeve bore taken along line 19-19 of FIG. 10;

FIG. 20 is an end view of a valve sleeve as employed in the engine;

FIG. 21 is a partial sectional view of the valve sleeve of FIG. 20 taken along line 21-21 thereof;

FIG. 22 is an end view of the other valve sleeve as employed in the engine;

FIG. 23 is a side view of a rotary valve of the steam engine as employed in the cylinder head shown in FIG. 18 and in a valve sleeve as shown in FIG. 21;

FIG. 24 is a sectional view along line 24-24 of FIG. 19;

FIG. 25 is a sectional view of the rotary valve as employed in the right end cylinder head, as viewed in FIG. 18;

FIGS. 26-29 are sectional views taken generally along lines 26-26, 27-27, 28-28, and 29-29 of FIG. 18 respectively, showing in part and schematically, the valve mechanisms;

FIG. 30 is a table showing a timing of the valves;

FIG. 31 is a bottom sectional view taken along line 31-31 of FIG. 10 showing the valve advance mechanism and oil return passages for the steam engines; and

FIG. 32 is a vertical sectional view taken along line 32-32 of FIG. 10 showing in part the lubrication conduit system for the steam engine.

BASIC POWER UNIT Now with reference to thd drawings and particularly FIG. 1 through 8, there is illustrated my basic power unit 10 employed in a two cycle internal combustion engine. It will be appreciated that although the illustrated engine is a gas engine my invention is not limited to that particular type of engine but is also adaptable for application upon a diesel engine or steam engine.

Power unit 10 as viewed in FIG. 1 consists of a pair of opposed cylinder, piston and rotor units 12, 12a mounted in axially alignment and operatively associated by means of common rotatable shaft 14. Units 12, 12a are mounted on base 15 through screws 16 and upstanding supports 17, 17a. Base 15 may be secured to a suitable foundation support 18 by means of bolts 19.

It will be appreciated from reviewing the drawings that units 12, 12a are mirror images of each other and may be described as opposing left and right units. Accordingly, the letter a is used to designate those elements of the right unit or unit 12a which have counterparts in the left unit, or unit 12.

Units 12, 12a include identically contructed and opposed housings 20, 20a having outer surfaces 2l, 21a and inner surfaces 22, 22a. Bolts 23 secure cylinder heads 24, 24a to housings 20, 20a with the inner surface of cylinder head flanges 25, 25a respectively abutting outer housing surfaces 21, 21a. Any suitable seal such as an aluminum seal may be used in securing the respective cylinder heads to the housings.

Housings 20, 20a have respective internal rotor bores 26, 26a of uniform diameter extending inwardly from surfaces 21, 21a to internal housing flanges 28, 28a respectively. Slotted cylindcrical skirt 30, 30a of cylinder heads 24, 24a extend into rotor bores 26, 26a and are dimensioned to engage in a slight interference fit therewith.

Seal bores 32, 32a extend respectively from housing inner surfaces 22, 22a inwardly to flanges 28, 28a and accommodate sealing means 33, 33a for suitably sealing the inner ends of housings 20, 20a about common shaft 14. Sealing means 33, 33a are secured in place by means of threaded seal plates 34, 34a each of which have suitable wrench adaptable heads 35 and are received in a threaded portion of bores 32, 32a. Gear 36 is securely mounted by suitable means (not shown) on 

1. In a power unit having a cylinder and a piston received for reciprocation therein and a drive shaft, means in axial alignment with said piston member for transforming reciprocal motion of said piston member into rotary motion of said drive shaft, said means comprising a hollow cylindrical rotor connected at one end to said drive shaft and having at its other end annular cam surface means coaxial with said piston member, said piston member being slidably receivable within said rotor at said other end, means guiding said piston member for reciprocation within said cylinder and said rotor and cam means on said piston member operatively engaging said cam surface means to transform reciprocal motion of said piston member into rotary motion of said drive shaft.
 2. The power unit of claim 1 including a housing having a cylindrical bore, said rotor being mounted in said housing for rotation in said bore, said piston guide means comprising diametically opposed pin means extending from said piston member, diametrically opposed slot means in said housing adjacent to and longitudinally parallel to said bore, and roller means rotatably mounted on each pin means and receivable for rotation in said slot means.
 3. The power unit of claim 2 wherein said piston cam means includes cam roller means rotatably mounted on said piston pin means intermediate said piston and said guide roller means, washer means on said pin means separating said cam rollers and guide rollers and said cam roller means operatively engaging said rotor cam surface means to transform reciprocal motion of said piston member into rotary motion of said drive shaft.
 4. The power unit of claim 3 wherein said rotor cam surface means comprises an endless sinusoidal track peripherally located between said piston member and said rotor bore, said track having two diametrically opposed power stroke cam surfaces and two diametrically opposed return stroke cam surfaces with intervening recesses and vertices between adjacent power stroke surfaces and return stroke cam surfaces whereby said opposed cam roller means engage said cam surfaces transforming reciprocal motion of said piston into rotary motion of said drive shaft.
 5. The power unit of claim 4 wherein said cam roller means are of generally frusto-conical shape, said cam surfaces being beveled outwardly, complementarily to said cam roller means whereby substantially rolling contact exists between said cam roller means and cam surfaces.
 6. The power unit of claim 5 wherein said cam roller means have a peripheral curvature whereby the contact between said beveled cam surfaces and cam roller means is substantially rolling point contact, said guide roller means being substantially of identical size and shape to said cam rollers and mounted on said pin means in confronting relationship thereto, said slot means being generally semi-circular in cross section and of such a radius whereby said roller guide means are received for rotation therein and effect substantially rolling point contact therewith.
 7. In a power unit having opposed first and second axially aligned cylinder and pistion assemblies wherein said pistons are reciprocal in said cylinders, means in axial alignment with and intermediate said assemblies for transforming reciprocal motion of each piston into rotary motion, said means comprising a drive shaft having opposed first and second rotor means secured to each shaft end, said first and second rotor means each comprising a hollow, cylindrical member having endless cam surface means, each piston being slidably receivable within its respective rotor and means guiding each of said pistons for reciprocal motion within its associated cylinder and rotor means, means associated with said first and second pistons whereby said pistons are caused to reciprocate in unison, said pistons each having cam means operatively engaging associated cam surface means whereby reciprocal motion of each piston is transformed into rotary motion of said drive shaft.
 8. The power unit of claim 7 wherein said first and second cam surface means each comprise two power stroke cam surfaces and two return stroke cam surfaces with intervening vertices and recesses, said rotor means and cam surfaces being angularly off-set substantially 90* whereby the vertices of said first cam surface are axially aligned with the recesses of said second cam surface means, said means associated with said first and second pistons being constructed whereby a power stroke of one of said pistons causing rotation of said drive shaft effects a return stroke of the other of said pistons and maintains the cam means of said other of said pistons substantially disengaged from the return stroke cam surface of its operatively associated rotor means during said return stroke.
 9. The power unit of claim 8 wherein said drive shaft has an axial bore therethrough, said means associated with said first and second pistons including first and second rod means connected to respective pistons and slidably received within said bore, said first and second rod means in contact with each other within said bore whereby said pistons are caused to reciprocate in unison, and the combined length of said first and second rod means maintaining the cam means of a piston on its return stroke substantially disengaged from the return stroke cam surfaces of its operatively associated rotor.
 10. The power unit of claim 8 wherein said drive shaft has an axial bore therethrough, said means associated with said first and second pistons including adjustable rod means interconnecting said pistons and slidably received within said bore whereby said pistons are caused to reciprocate in unison, and the length of said rod means being adjusted whereby the cam means of a piston on its return stroke is maintained substantially disengaged from the return stroke cam surfaces of its operatively associated rotor.
 11. The power unit of claim 9 including opposed first and second housings each having cylindrical bores and diametrically opposed slot means adjacent and axially parallel to said respective bores, said first and second rotor means mounted in said housing for rotation in Respective first and second bores, said piston guide means of said first and second pistons including diametrically opposed pin means extending from said pistons and receivable in said diametrically opposed slot means in the respective housings, said slot means in the first housing being in axial alignment with the slot means in said second housing, said guide means further including rollers rotatably mounted on each said pin means and receivable in said slot means, said first and second piston cam means including cam rollers rotatably mounted on said pin means intermediate respective pistons and said guide rollers, and each said cam rollers being of frusto-conical shape and said first and second cam surfaces being complementarily bevelled to said cam rollers.
 12. The power unit of claim 7 wherein said first and second cam surface means each comprise two power stroke cam surfaces and two return stroke cam surfaces with intervening vertices and recesses, the vertices and recesses of said first cam surface means being axially aligned with the vertices and recesses of said second surface means, said first piston cam means being angularly offset substantially 90* from said second piston cam means, said rod means being of such length whereby a power stroke of one of said pistons, transformed into rotary motion of said drive shaft through the power stroke cam surface of the operatively associated rotor means, effects the return stroke of the other of said pistons and maintains the cam means of said other piston substantially disengaged from the return stroke cam surface of the rotor means operatively associated therewith.
 13. The power unit of claim 12 including first and second housings having cylindrical bores for containing said first and second rotors, said piston guide means of said first and second pistons each including diametrically opposed pin means extending from said piston and receivable in diametrically opposed slot means in the respective housings, said slot means in the first housing being angularly offset substantially 90* from the slots in said second housing, said piston guide means including guide rollers rotatably mounted on each pin means and receivable in said slot means, said first and second piston cam means including cam rollers rotatably mounted on said pin means intermediate respective said piston and guide rollers, and each of said cam rollers being of frusto-conical shape and each of said first and second cam surface means being bevelled complementarily to said cam rollers.
 14. In an engine having housing means, and opposed cylinder head means secured to opposite ends of said housing, an output drive shaft rotatably mounted within and extending axially through said housing means and cylinder head means, a plurality of power units contained within said housing means and cylinder head means and circumscribing and axially parallel to said output shaft, each of said power units having a pair of opposed, axially aligned cylinder and piston assemblies and having means mounted for rotation within said housing intermediate said opposed assemblies and operatively associated with said opposed pistons for transforming reciprocal motion of each piston into rotary motion of said means, said means including opposed hollow, cylindrical rotor means connected to opposite ends of a unit shaft and rotatably mounted in said housing in axial alignment with said opposed piston and cylinder assemblies, each said rotor means having annular cam surface means and each piston of each assembly being slidably receivable within its associated rotor means, means for guiding each piston for reciprocation within its associated cylinder and rotor means, means associated with each pair of opposed unit pistons for causing reciprocation thereof in unison, means in said housing for coupling each of said unit shafts to said output shaft, and valving means in each of said cylinder heads for controlling the flow of working fluid through the cylinders, and cam means on each piston operatively engaging the cam surface means of its associated rotor means whereby reciprocal motion of each piston in valve controlled sequence is transformed into rotary motion of said output drive shaft.
 15. The engine of claim 14 wherein each said unit shaft has an axial bore therethrough, said means associated with each pair of pistons in a unit including rod means connected to each piston and slidably received within said bore, the length of said rod means being such whereby a power stroke of one of said pair of pistons effects a return stroke of the opposed piston of said pair and maintains the cam means of said opposed piston disengaged from the cam surfaces of its operatively associated rotor means during said return stroke.
 16. The engine of claim 15 wherein said rod means comprises a rod connected to each of said opposed pistons in a power unit, each rod slidably received within said bore and the ends of said rods within said bore in contact with each other, and the combined length of said rods being such to maintain disengagement between the piston cam means of a piston on its return stroke and the cam surface means of its operatively associated rotor means.
 17. The engine of claim 15 wherein said rod means comprises a rod interconnecting said pair of opposed pistons of each unit, at least one end of said rod being adjustably connected to one of said pair of opposed pistons, and removable means in the top of that piston permitting selective adjustment of the separation between said opposed pistons.
 18. The engine of claim 14 wherein the opposed rotor means for each unit are rotatably mounted within cylindrical rotor bores in said housing, said piston guide means for each piston including diametrically opposed pin means extending from each piston and diametrically opposed slot means in said housing adjacent each rotor bore and longitudinally parallel therewith, the slot means of each power unit being planar and perpendicular to a radial line between said output drive shaft and said power unit, and guide rollers rotatably mounted on each said pin means and receivable for rotation in an associated slot means.
 19. The engine of claim 18 wherein said rotor cam surface means in each power unit comprises two power stroke cam surfaces and two return stroke cam surfaces with intervening vertices and recesses, said unit rotors and respective cam surfaces being angularly offset substantially 90* whereby the vertices of the cam surface means of one of said pistons in a unit are axially aligned with the recesses of the cam surface means of the other of said pistons in the unit, and said means associated with said pistons for causing their reciprocation in unison being of such length whereby a power stroke of each one of said pistons in said units, causing rotation of said respective unit shaft, effects a return stroke of the other of each of said pistons in said units and maintains the piston cam means of said other of said pistons substantially disengaged from the return stroke cam surface of its operatively associated rotor means during said return stroke.
 20. The engine of claim 19 wherein said piston cam means include cam rollers rotatably mounted on said pin means intermediate said piston and guide rollers, washer means on each said pin means separating each cam roller from each said guide roller, and said cam rollers operatively engaging said power stroke cam surfaces to transform controlled reciprocal movement of each piston into rotary motion of its associated unit shaft.
 21. The engine of claim 14 wherein said valving means includes valve sleeves rotatable within bores in said cylinder heads, and rotary valves rotatably received in said sleeves and operatively driven by said output shaft, a valve advance mechanism including means operatively driven by said output shaft and responsive to an increase in the rotative speed thereof to simultaneously rotate each of said sleeves within said cylinder head valve bores in a dirEction counter to the direction of rotation of said associated rotary valve to advance valve timing.
 22. The engine of claim 21 having four power units circumscribing said output shaft, a valving means in each cylinder head for each of two power units and said valve advance mechanism including means below said housing operatively connected to said output shaft, said means being continuously rotated with rotation of said output shaft and including means responsive to centrifugal force for simultaneously effecting valve advance of each of said valving means through linkage means between said valve advance rotating means and respective valve sleeves.
 23. The engine of claim 14 in combination with a lubrication system, said system including an oil reservoir and pump mounted below said housing, said pump being operatively driven by said engine, said lubrication system further including first conduit means extending upwardly through said housing and about said output drive shaft for carrying lubricant from said pump to said output drive shaft and the uppermost power units in said engine, second conduit means between said uppermost power units and the lowermost power units and third conduit means between said lowermost power units and said reservoir whereby lubricant is provided to reciprocating and rotating elements within said housing bore, means about said output drive shaft for conducting lubricant from said first conduit means along said output shaft to said cylinder heads for lubrication of the valving means contained therein, and fourth conduit means in said cylinder heads and housing for returning lubricant for said valving means to said reservoir.
 24. The engine of claim 23 having four power units circumscribing said output shaft and peripherally spaced thereabout, two of said four units being horizontally planar and comprising the uppermost power units and two of said units, each vertically below one of said uppermost units, comprising the lowermost units, said means coupling said unit shafts of said power units to said output shaft comprising gear means secured to and mounted for rotation with respective shafts in gear chamber means within the center of said housing, said first conduit means including substantially vertical and horizontal passages in said housing on either side of said gear chamber means, said vertical passages extending upwardly in said housing between said vertically aligned power units and about said output drive shaft and said horizontal passages extending from upper closed ends of each of said vertical conduits into an upper part of said uppermost units adjacent the respective rotor bores thereof, said second conduit means including substantially vertical passages between said vertically aligned power units, and said third conduit means including passages from a bottom part of each said lowermost units adjacent the rotor bores thereof, said passages extending through said housing into said oil reservoir.
 25. The engine of claim 24 wherein said piston guide means for each unit comprises diametrically opposed slot means in said housing adjacent and longitudinally parallel to the rotor bore in each unit, diametrically opposed pin means on each piston of said units and guide rollers rotatably mounted on said pin means and receivable for rotation in said slot means, the slot means of each power unit being planar and perpendicular to a radial line between said output drive shaft and said power shaft, and each of the passages of said first, second and third conduit means leading into and out of said units adjacent the slot means associated therewith.
 26. The engine of claim 18 further including working fluid exhaust catch means intermediate the ends of said housing means and respective cylinder head means, said engine having four power units circumscribing said output shaft and said coupling means between each unit shaft and said output drive shaft comprising gear means, said unit gears each having a 1:1 ratio with said drive shaft gear, a vaLving means each cylinder head for each of two piston units, each said valving means including a rotary valve mounted for rotation in valve bores in said cylinder head means and comprising a gear portion and working fluid control portion, a valve drive gear secured to said output shaft within each cylinder head means and in mesh with the valve gear portions of associated valves for positive drive thereof, working fluid passages to said rotary valves, inlet and exhaust channels in said working fluid control portion of said valves, and passages between said valve bores and associated cylinders and between said bores and said exhaust catch means, whereby rotation of said valves controls the flow of working fluid through said assemblies. The engine of claim 26 wherein the mesh between said valve drive gears and said valve gear portions and consequently the timed sequence of rotation of the valves is such to provide a simultaneous firing of diagonally opposed cylinder and piston assemblies very 45* of rotation of said output drive shaft.
 28. The engine of claim 26 wherein the mesh between said valve drive gears and said valve gear portions and consequently the timed sequence of rotation of the valves is such to provide a single firing of a cylinder and piston assembly every 22 1/2 * of rotation of said output drive shaft.
 29. The power unit of claim 10 including opposed first and second housings each having cylindrical bores and diametrically opposed slot means adjacent and axially parallel to said respective bores, said first and second rotor means mounted in said housing for rotation in respective first and second bores, said piston guide means of said first and second pistons including diametrically opposed pin means extending from said pistons and receivable in said diametrically opposed slot means in the respective housings, said slot means in the first housing being in axial alignment with the slot means in said second housing, said guide means further including rollers rotatably mounted on each said pin means and receivable in said slot means, said first and second piston cam means including cam rollers rotatably mounted on said pin means intermediate respective pistons and said guide rollers, and each said cam rollers being of frusto-conical shape and said first and second cam surfaces being complementarily bevelled to said cam rollers. 